Closed-Form Frequency Dependent Gate-to-Channel Capacitance Model for Submicron MOSFET's

A new model of the gate-to-channel capacitance is proposed including the transmission line effects, not only for strong inversion but also for moderate and weak inversion regimes, which gives a good description of experimental capacitance curves. This is achieved by expressing the channel conductance in function of the inversion layer concentration. Quantum effects in the distribution of the inversion charge are taken into account by the introduction of a mean centroid, which is related to an effective capacitance area. This effective area is smaller than the real one due to nonuniform, surface conductivity, which is attributed to a random doping distribution giving fluctuations of the surface potential.